1. Field of the Invention
The present invention relates to a wireless communication system and, in particular, to a method for activating a secondary carrier in addition to the primary carrier in a Long Term Evolution (LTE) system supporting Carrier Aggregation.
2. Description of the Related Art
With the rapid advance of wireless communication technology, the communication system has evolved to the 4th Generation mobile communication systems such as Long Term Evolution (LTE) system. The LTE system adopts various techniques to meet the increased traffic requirements and, Carrier Aggregation is one of these techniques. The carrier aggregation is a technique capable of increasing the data rate in proportion to the number of aggregated carriers including plural secondary carrier as well as the primary carrier between a User Equipment (UE) and an evolved Node B (eNB) as compared to the conventional system using a single carrier. In LTE, the primary cell is referred to as PCell and the secondary cell is referred to as SCell.
In order to use the carrier aggregation technique, it is inevitable that the complexity increases to control the PCell and the SCells. That is, there is a need of control to determine the SCell(s) to be configured for use along the PCell and to be activated for actual use.
There is therefore a need of a detailed procedure for activating an SCell. That is, it is necessary to specify the operation of the UE when an SCell activation command is received from the eNB.